Its wingspan is about 40 mm. The forewings are coloured in two shades of brown divided by a line from the base to the wingtip. The anterior part is pale brown, whereas the posterior part is darker brown. Hindwings off white. Eggs are yellow and pubescent. The caterpillar is hairy with a broad black line along the back. There are four brown tussocks. Black line is bordered by yellow patches on each segment and each yellow patch having a red line through it. Two red glands found on the back of the two abdominal segments. There are two black hair-pencils found on the prothorax.[5]
It is a minor pest on paddy, where the attack by caterpillar can result defoliation. Damage can be minimized by using light traps or using chlorpyrifos.[9] A braconid parasitoid wasp Microplitis pennatula is known to induces rapid behavioral changes in the parasitized host, which is the caterpillar of P. pennatula.[10]
^Herbison-Evans, Don & Crossley, Stella (27 May 2017). "Psalis pennatula (Fabricius, 1793)". Australian Caterpillars and their Butterflies and Moths. Retrieved 13 October 2018.
